Method for the control of a wireless communications link for mitigating adjacent satellite interference

ABSTRACT

A method for remotely and dynamically controlling adjacent satellite interference comprising monitoring one or more off-axis signals emitted by one or more remote transmitters; determining whether one or more of the off-axis signals is creating adjacent satellite interference (ASI), off axis emissions and inband interference that is higher than a predetermined level of acceptable interference, and transmitting a control signal to at least one of the one or more remote transmitters in response to the determination that the one or more off-axis signals is creating interference that is higher than the predetermined level of acceptable interference, the control signal initiating an adjustment to one or more transmission parameters of the one or more remote transmitters such that interference resulting from the one or more off-axis signals emitted by the one or more remote transmitters is reduced or eliminated.

CROSS REFERENCE TO RELATED APPLICATIONS

This document is a Division of U.S. patent application Ser. No.13/162,483 entitled “A Method for the Control of a WirelessCommunications Link for Mitigating Adjacent Satellite Interference”filed Jun. 16, 2011 to Beeler et al., now pending, which applicationclaims the benefit of the filing date of U.S. Provisional PatentApplication No. 61/451,196, entitled “A Method for Adaptive Control ofModulation, Forward Error Correction (FEC) Rate Coding, Power, Spreadingand Bandwidth for the Control of a Wireless Communications Links forMitigating Adjacent Satellite Interference (ASI) and Overcoming InbandInterference” to Michael Beeler, et al., which was filed on Mar. 10,2011, the disclosure of which is hereby incorporated entirely byreference herein.

BACKGROUND

1. Technical Field

Aspects of this document relate generally to telecommunication systemsand techniques for transmitting data across a telecommunication channel.

2. Background Art

With the introduction of Communication on the Move (COTM) orCommunications on the Pause (COTP) systems, commonly referred to asmobile terminal(s), there is a growing need and great concern to controlthe level of interference caused by small aperture antennas.Additionally, small-aperture static terminals exhibit the sameinterference issues, so both a mobile and a static terminal willgenerically be referred to as “terminals.” Interference that may becaused by the terminals may be in the form of Adjacent SatelliteInterference (ASI), where the terminal's small aperture antenna producesa wide beam width resulting in adjacent satellites being illuminated,thereby resulting in interference to services on adjacent satellites.Larger antennas produce narrower beam widths, but they are generallyused less in mobile or nomadic applications.

Additionally, a terminal attempting to communicate over a satellite linkmay become degraded or interfered with by other terminals, bothcorrectly assigned and not correctly assigned to their bandwidth,resulting in interference that degrades the communication path to thepoint where the terminal may not reliably operate in the given bandwidththat has been assigned.

SUMMARY

Aspects and applications of the disclosure presented here are describedbelow in the drawings and detailed description. Unless specificallynoted, it is intended that the words and phrases in the specificationand the claims be given their plain, ordinary, and accustomed meaning tothose of ordinary skill in the applicable arts. The inventors are fullyaware that they can be their own lexicographers if desired. Theinventors expressly elect, as their own lexicographers, to use only theplain and ordinary meaning of terms in the specification and claimsunless they clearly state otherwise and then further, expressly setforth the “special” definition of that term and explain how it differsfrom the plain and ordinary meaning Absent such clear statements ofintent to apply a “special” definition, it is the inventors' intent anddesire that the simple, plain and ordinary meaning to the terms beapplied to the interpretation of the specification and claims.

According to a first aspect of the disclosure, a method for remotely anddynamically controlling adjacent satellite interference may comprisemonitoring one or more off-axis signals emitted by one or more remotetransmitters, determining whether one or more of the off-axis signals iscreating adjacent satellite interference (ASI) that is higher than apredetermined level of ASI, and transmitting a control signal to atleast one of the one or more remote transmitters in response to thedetermination that the one or more off-axis signals is creating ASI thatis higher than the predetermined level of ASI, the control signalinitiating an adjustment to one or more transmission parameters of theone or more remote transmitters such that ASI resulting from the one ormore off-axis signals emitted by the one or more remote transmitters isreduced or eliminated.

Particular implementations may comprise one or more of the followingfeatures and/or steps. The monitoring may occur on one or moresatellites adjacent to a predetermined satellite to which one or moresignals is to be transmitted. At least one of the one or moretransmission parameters may be a power spectral density of the one ormore signals transmitted by the one or more remote transmitters. Thepower spectral density of the one or more signals may be adjusted bychanging a modulation index. The power spectral density of the one ormore signals may be adjusted by changing a forward error correctionrate. The power spectral density of the one or more signals may beadjusted by changing a spread factor. The power spectral density of theone or more signals may be adjusted by changing a signal bandwidth. Thepower spectral density of the one or more signals may be adjusted bychanging a center frequency. The power spectral density of the one ormore signals may be disabled.

According to a second aspect of the disclosure, a method for dynamicallycontrolling transmission parameters for reducing inband interference maycomprise monitoring one or more signals emitted by one or more remotetransmitters, determining whether inband interference exists from atleast one of the one or more remote transmitters that is higher than apredetermined level of inband interference, and automaticallytransmitting a control signal to the remote transmitter in response to adetermination that the inband interference is higher than thepredetermined level of inband interference, the control signal adjustingone or more transmission characteristics of the one or more remotetransmitters such that the inband interference is reduced.

Particular implementations may comprise one or more of the followingfeatures and/or method steps. The one or more remote transmitters mayall be located within a common network and may be configured tocommunicate among the one or more remote transmitters. The one or moresignals monitored may be off-axis signals and the monitoring may occuron one or more satellites adjacent to a predetermined satellite to whichthe one or more signals is to be transmitted. At least one of the one ormore transmission parameters may be a power spectral density of the oneor more signals transmitted by the one or more remote transmitters. Atleast one of the one or more transmission parameters may be a modulationindex. At least one of the one or more transmission parameters may be aforward error correction rate. At least one of the one or moretransmission parameters may be a spread factor. At least one of the oneor more transmission parameters may be a signal bandwidth. At least oneof the one or more transmission parameters may be a center frequency.

According to a third aspect of the disclosure, a system for remotely anddynamically controlling adjacent satellite interference may comprise amonitoring device configured to monitor one or more off-axis signalsemitted by a remote transmitter and determine whether one or more of theoff-axis signals is creating adjacent satellite interference (ASI) thatis higher than a predetermined level of ASI, and a transmitterconfigured to automatically transmit a control signal to the remotetransmitter in response to a determination that the one or more off-axissignals is creating ASI that is higher than the predetermined level ofASI, the control signal configured to adjust one or more transmissionparameters such that ASI resulting from the one or more off-axis signalsemitted by the remote transmitter is reduced or eliminated.

Particular implementations may comprise one or more of the followingfeatures and/or components. The monitoring device may be located on oneor more satellites adjacent to a predetermined satellite to which one ormore signals is to be transmitted. At least one of the one or moretransmission parameters may be a power spectral density of the one ormore signals transmitted by the remote transmitter. The control signalmay be further configured to adjust the power spectral density of theone or more signals is adjusted by changing a modulation index. Thecontrol signal may be further configured to adjust the power spectraldensity of the one or more signals by changing a forward errorcorrection rate. The control signal may be further configured to adjustthe power spectral density of the one or more signals by changing aspread factor. The control signal may be further configured to adjustthe power spectral density of the one or more signals by changing asignal bandwidth. The control signal may be further configured to adjustthe power spectral density of the one or more signals by changing acenter frequency. The power spectral density of the one or more signalsmay be disabled.

According to a fourth aspect of the disclosure, a system for dynamicallycontrolling transmission parameters for reducing inband interference maycomprise a monitoring device configured to monitor one or more signalsemitted by a remote transmitter and determine whether inbandinterference exists that is higher than a predetermined level of inbandinterference, and a transmitter configured to transmit a control signalto the remote transmitter in response to a determination that the inbandinterference is higher than the predetermined level of inbandinterference, the control signal configured to adjust one or moretransmission parameters such that the inband interference is reduced.

Particular implementations may comprise one or more of the followingfeatures and/or components. The one or more remote transmitters may allbe located within a common network and are configured to communicateamong the one or more remote transmitters. The monitoring device may belocated on one or more satellites adjacent to a predetermined satelliteto which the one or more signals is to be transmitted and may further beconfigured to monitor one or more off-axis signals. At least one of theone or more transmission parameters may be a power spectral density ofthe one or more signals transmitted by the remote transmitter. At leastone of the one or more transmission parameters may be a modulationindex. At least one of the one or more transmission parameters may be aforward error correction rate. At least one of the one or moretransmission parameters may be a spread factor. At least one of the oneor more transmission parameters may be a signal bandwidth. At least oneof the one or more transmission parameters may be a center frequency.

The inventors are also aware of the normal precepts of English grammar.Thus, if a noun, term, or phrase is intended to be furthercharacterized, specified, or narrowed in some way, then such noun, term,or phrase will expressly include additional adjectives, descriptiveterms, or other modifiers in accordance with the normal precepts ofEnglish grammar. Absent the use of such adjectives, descriptive terms,or modifiers, it is the intent that such nouns, terms, or phrases begiven their plain, and ordinary English meaning to those skilled in theapplicable arts as set forth above.

Further, the inventors are fully informed of the standards andapplication of the special provisions of 35 U.S.C. §112, ¶6. Thus, theuse of the words “function,” “means” or “step” in the Description,Drawings, or Claims is not intended to somehow indicate a desire toinvoke the special provisions of 35 U.S.C. §112, ¶6, to define theinvention. To the contrary, if the provisions of 35 U.S.C. §112, ¶6 aresought to be invoked to define the claimed disclosure, the claims willspecifically and expressly state the exact phrases “means for” or “stepfor, and will also recite the word “function” (i.e., will state “meansfor performing the function of [insert function]”), without alsoreciting in such phrases any structure, material or act in support ofthe function. Thus, even when the claims recite a “means for performingthe function of . . . ” or “step for performing the function of . . . ,”if the claims also recite any structure, material or acts in support ofthat means or step, or that perform the recited function, then it is theclear intention of the inventors not to invoke the provisions of 35U.S.C. §112, ¶6. Moreover, even if the provisions of 35 U.S.C. §112, ¶6are invoked to define the claimed disclosure, it is intended that thedisclosure not be limited only to the specific structure, material oracts that are described in the preferred embodiments, but in addition,include any and all structures, materials or acts that perform theclaimed function as described in alternative embodiments or forms of theinvention, or that are well known present or later-developed, equivalentstructures, material or acts for performing the claimed function.

The foregoing and other aspects, features, and advantages will beapparent to those artisans of ordinary skill in the art from theDESCRIPTION and DRAWINGS, and from the CLAIMS.

BRIEF DESCRIPTION OF THE DRAWINGS

Implementations will hereinafter be described in conjunction with theappended drawings, where like designations denote like elements, and:

FIG. 1 depicts the prior art having fixed transmission parameters inwhich the resulting radiation pattern does not cause ASI.

FIG. 2 depicts the prior art having fixed parameters in which theresulting radiation pattern does cause ASI.

FIG. 3 shows an implementation of a method of measuring ASI on adjacentsatellites and adjusting transmission parameters to reduce ASI.

FIG. 4 shows a plurality of radiation patterns from various antennas.

FIG. 5 shows a typical antenna emissions plot with a power spectraldensity (PSD) mask in which the main lobe pointing at the boresight andthe side lobes are contained under the PSD mask.

FIG. 6 shows an antenna emissions plot resulting from an antenna inwhich transmission exceeds the PSD mask and an antenna emissions plotfor an implementation of a method of increasing signal bandwidth whilechanging modulation, coding, power, and spreading parameters to reduceASI.

FIG. 7 shows the result of an implementation of a method of overcominginband interference by increasing occupied signal bandwidth and usingspread spectrum technology.

FIG. 8 is a logic flow diagram of an implementation of a method ofreducing ASI interference.

FIG. 9 is a logic flow diagram of an implementation of a method ofreducing inband interference.

DESCRIPTION

This disclosure, its aspects and implementations, are not limited to thespecific components, power control, modulation, coding or spreading, ormethods disclosed herein. Many additional components and assemblyprocedures known in the art consistent with a method for adaptivecontrol of modulation, Forward Error Rate (FEC) coding, power,spreading, and bandwidth for the control of a wireless communicationslinks for mitigating Adjacent Satellite Interference (ASI) andovercoming inband interference are in use with particularimplementations from this disclosure. Accordingly, for example, althoughparticular implementations are disclosed, such implementations andimplementing components may comprise any components, models, versions,quantities, and/or the like as is known in the art for such systems andimplementing components, consistent with the intended operation.

The described methods provide a mechanism for adaptively mitigating theASI produced by a transmission terminal by adaptively controlling themodulation index, Forward Error Rate (FEC) coding, uplink power, spreadfactor, and/or bandwidth. Each parameter may be adjusted alone or inconcert to mitigate ASI by the terminal or mitigate degraded linkconditions or interference by another terminal to achieve reliablecommunications.

The methods described herein are intended to provide the ability forsomeone skilled in the art, for example, a communications software ortest engineer, network operator, equipment manufacturer or othercommunications and network specialist to utilize the described methods.

This disclosure relates to, but is not limited to, methods foradaptively controlling the modulation, Forward Error Correction (FEC)rate coding, power, spreading, and bandwidth for a communications linkfor the mitigation of ASI caused by communication devices such as mobileterminals and the ability to overcome degraded link conditions orinterference (intentional or unintentional) by other terminals. The termadaptive, when introduced into a communications link, is not new in theart. As an example of existing art, the European TelecommunicationsStandards Institute (ETSI) EN 302 307, the contents of which is hereinincorporated entirely by reference, introduces a method knows asAdaptive Coding and Modulation (ACM) where the modulation may range fromQuaternary Phase-Shift Keying (QPSK) to 32-Ampltude Phase-Shift Keying(32-APSK) modulation and the Forward Error Correction (FEC) may beadjusted in concert to provide operation at a Symbol Energy to NoiseDensity, commonly represented in the art as Es/No, expressed in decibels(10*Log₁₀(Es/No)). As a second example of existing art, the wirelessterrestrial (mobile phone) industry uses a technique known as OrthogonalVariable-Spreading-Factor (OVSF) where orthogonal spreading codes andspread factors are distributed to compensate for changing conditions. Afinal example of existing art is WO 2008/129509 A1 to Shiron SatelliteCommunications, Ltd., the contents of which is herein incorporated byreference, that describes a Method and Apparatus for Compensation forWeather Based Attenuation in a Satellite Link.

Link degradation is presently addressed in the art, but there is nocompensation for dynamically addressing the ASI contribution orovercoming interference in a dynamic fashion with the exception of beamforming as described in U.S. Pat. No. 5,754,138 by Turcotte, et al, thedisclosure of which is herein incorporated by reference. In thedescribed art, the antenna patterns are fixed and there are nocoefficients to be altered for changing the electromagnetic beam(radiation pattern of the antenna).

Therefore, given that the antenna's beam configuration is a fixedpattern from the terminal, addressing the contribution of ASI andovercoming the interference may be done through the use of adjusting thetransmission parameters in particular implementations of the describedmethods.

The described methods provide an approach for both addressing andcontrolling the Adjacent Satellite Interference (ASI) contributed by aremote terminal as well as inband interference caused by interferingcarriers within the same bandwidth of the terminal under control usingthese methods. Particular implementations described herein may employdigital signal processing (DSP) techniques such as, but not limited to,power control, modulation, coding and spreading techniques which caneasily be implemented in, but are not limited to, a Field-ProgrammableGate Array (FPGA), Programmable Logic Device (PLD), ProgrammableIntegrated Circuit (PIC), Digital Signal Processor (DSP), ApplicationSpecific Integrated Circuit (ASIC) or microprocessors.

Particular implementations of a method for adaptive control ofmodulation, Forward Error Correction (FEC) rate coding, power,spreading, and bandwidth for the control of a wireless communicationslinks for mitigating Adjacent Satellite Interference (ASI) andovercoming inband interference as disclosed herein may be specificallyemployed in satellite communications systems. However, as it will beclear to those of ordinary skill in the art from this disclosure, theprinciples and aspects disclosed herein may readily be applied to anyelectromagnetic (IF, RF and optical) communications system, such ascellular phone or terrestrial broadcast network without undueexperimentation.

The ability to dynamically provide feedback to a transmission network tomodify the transmission parameters is not a novel concept. Fortraditional transmission networks that employ dynamic power control oradaptive coding and modulation methods currently in use in the existingart, the parameters are limited to one, two or three moments ofmovement, e.g. power control, modulation and coding or spread factor.The described methods may take advantage of up to five moments ofmovement to address the ASI (inbound from the terminal) and inbandinterference (inbound from the terminal) in a dynamic fashion. Althoughsmaller antennas' electromagnetic (EM) beam widths are wider than largerantennas, the use of smaller antennas is becoming more common. Anembodiment of a method is also described herein to address the drawbacksof using these wider beam width antennas.

Some embodiments of the described methods do not limit the feedbackchannel to using the same medium as the desired channel. In a particularembodiment, both the forward and return channel paths are over the samemedium, but this is not a requirement. Instead, the forward path may beover a satellite link, and the return channel maybe via a terrestrialmicrowave link, terrestrial connection, and optical connection or in themost primitive method a visual signal. Techniques such as spreadspectrum or embedded spread spectrum may be used.

FIG. 1 shows a traditional wireless satellite network in the existingart supporting communications between remotely-distributedcommunications locations. This type of satellite link is without theability to dynamically monitor, address or correct the ASI or inbandinterference, and is designed for the a priori worst case conditions. Inmost cases, the worst case conditions are established to provide a linkavailably in the 99^(th) percentile. Once the communicationsconfiguration is set, the terminal operates with no regard to correctingtransmission or impairment issues that may be experienced. Fixedcommunications sites are typically designed to operate in this fashion.Thus, when conditions change and a terminal exceeds acceptable limitsfor operation, no corrective action results. For a COTM or COTPterminal, as the terminal is in motion or is reconfigured, changes maytake place resulting in improper operation. In a statically configurednetwork, a single terminal may cause ASI resulting in interference toservices that are not associated with the terminal's mission. For mobileterminal applications, this manner of operation may be problematic,since the terminal may be in motion or moving from location to location,and may be changing transmission parameters as it does so. As shown, theresult of transmission in FIG. 1 is a fixed radiation pattern 100 havingradiation to the adjacent satellite 110 being below the requiredregulatory limits, thus providing an acceptable amount of ASI to thesatellites to the left and right of the desired satellite 120 in theboresight. Satellites 110 are shown as spaced −2 degrees and +2 degreesfrom the desired satellite 120. This is the minimum spacing allowed inthe orbital arc over North America for Ku-band.

FIG. 2 shows the prior art where all the parameters are fixed and theresulting radiation pattern 200 is fixed, resulting in radiation to theadjacent satellites 110 rising above the desired or required regulatorylimits, thus exceeding the ASI to the satellites to the left and rightof the desired satellite 120 in the boresight. The result isinterference with the adjacent satellites 110, since the side lobeenergy is operating above an acceptable limit, resulting in energy beinginjected into the adjacent satellites 110 above an acceptableestablished regulatory limit. The prior art does not address the ASIcaused by these terminals in a manner other than by beam forming.

FIG. 3 shows an implementation of the described methods in which the ASIcaused by a transmission from a remote terminal 210 is measured onsatellites 300 that are adjacent to the desired satellite 220 andtransmission parameters are adjusted to lower the ASI to an acceptablelevel so as to reduce or eliminate interference. This adjustment mayinclude removal of transmission power. A feedback path is provided todynamically control the transmission characteristics from the terminalto address the ASI and inband interference mitigation. In oneapplication, this feedback path may also be used to turn off thetransmission power of the terminal. Implementations may use spreadspectrum or embedded spread spectrum technology in transporting thecommunications signal.

FIG. 4 shows three different antenna configurations such that theradiation patterns are different for each type of antenna. The antennapatterns 400, 410, 420 shown may be the same size and geometry, but theuse of different manufacturing techniques creates a difference in how aresulting beam pattern appears from each antenna. As shown, the powerspectral density (PSD) mask 430 contains the main lobe pointing at theboresight and the side lobes. As can be observed, given the differentradiation patterns 400, 410, 420 from the antennas, no singleconfiguration or static configuration can solve the problem. Using animplementation of the described method, the radiation pattern of theantenna becomes less of a concern, since the dynamic monitoring andcontrol ensures the terminal's radiation pattern from the antenna willbe kept to an acceptable level. It is noteworthy that the narrower theantenna's beam into boresight the “sharper” or more directive theantenna is considered to be.

FIG. 5 shows a typical power spectral density (PSD) mask 430 in whichthe main lobe of the antenna radiation pattern 500 is pointing at theboresight and the side lobes are all contained under the PSD mask 430.Shown in FIG. 5 are the results of using an implementation of thedisclosed method to alter the transmission parameters from thetransmitting terminal thereby reducing the power level of the off axisemissions to prevent or reduce the ASI in a dynamic fashion.

FIG. 6 shows the radiation pattern 600 of a terminal in which thetransmission power exceeds the PSD mask 430. This pattern results whenthe output power of the antenna is higher than the allowed or desiredlimit. Using an implementation of the described method, a combination ofany or all of the modulation, FEC coding, power and/or spread factor maybe modified to lower the ASI. For example, as shown, some configurationsof transmission parameters result in the main lobe (boresight) to fallwithin the PSD mask 430 while the side lobe energy is still too high tobe contained within the PSD mask 430. In this circumstance, an increasein bandwidth and spreading may be required to reduce the power level sothat all lobes fall within the PSD mask 430.

Currently in the art, the modulation index is reduced from a high ordermodulation such as 32-Amplitude Phase-Shift Keying (32-APSK) to the nextlower modulation index such as 16-APSK, 8-PSK or even QuaternaryPhase-Shift Keying (QPSK). Additionally, another moment of movement isthe FEC coding. As link conditions are degrading, the FEC is reduced.The modulation and coding (MODCOD) are reduced in concert until thelowest available MODCOD is reached. An example of the use of adaptivecontrol is defined in the European Telecommunications StandardsInstitute (ETSI) EN 302 307 and in WIPO 2008/129509 A1 by ShironSatellite Communications, the disclosures of which are hereinincorporated entirely by reference. Thus, in conventional systems, amethod may provide a range of movement of no more 20 dB of compensationand addresses only the link degradation and not the resulting ASI orinterference.

As a specific example of how the PSD may be managed, assume a system isconfigured to operate with a maximum input power density of −14 dBW/4kHz as recommended by the Federal Communications Commission (FCC) formobile terminal operation in the United States. In the prior art, theterminal is configured to ensure the −14 dBW/4 KHz is maintained, butthis limits the operation of the terminal in a manner that at no timecan the power be increased or set dynamically to be increased ordecreased to overcome link degradations. A particular embodiment of thedescribed methods continually monitors the terminal's transmission toensure the terminal is transmitting at optimal power, but not so highthat it results in adjacent satellite interference. Assuming the maximumPSD provided by the terminal is −14 dBW/4 KHz and the spectral maskfollows an example of:

15−10 Log(N)−25 Log Θ dBW/4 KHz for 1.5°≦Θ≦7°

−6−10 Log(N) dBW/4 kHz for 7°≦Θ≦9.2°

18−10 Log(N)−25 Log ΘdBW/4 kHz for 9.2°≦Θ≦48°

−24−10 Log(N) dBW/4 kHz for 48°≦Θ≦85°

−14−10 Log(N) dBW/4 kHz for 85°≦Θ≦180°

The resulting limits are shown as the PSD limits on FIGS. 4 through 6.To adjust the PSD to be below the desired limits, each parameter may beadjusted and the resulting changes are shown in the following examples:

Example 1 is a non-limiting example of how the modulation index may beadjusted resulting in the following correction to the PSD:

32-APSK to 16-APSK: PSD is lowered by 3.0 dB

16-APSK to 8PSK: PSD is lowered by 3.0 dB

8PSK to QPSK: PSD is lowered by 3.0 dB

QPSK to BPSK: PSD is lowered by 3.0 dB

Therefore the PSD may be lowered by the modulation index by a range of12.0 dB.

Example 2 is a non-limiting example for the Forward Error Correction(FEC) coding of how a generic FEC code may be adjusted resulting in thefollowing correction to the PSD:

9/10 FEC to ¾ FEC: PSD is lowered by approximately 3.0 dB

¾ FEC to ½ FEC: PSD is lowered by approximately 3.0 dB

½ FEC to ¼ FEC: PSD is lowered by approximately 3.0 dB

Example 3 is a non-limiting example of how the Spread Factor may beadjusted resulting in the following correction to the PSD:

No spreading to a spread factor of 2: PSD is lowered by 3.0 dB

Spread factor of 2 to 4: PSD is lowered by 3.0 dB

Spread factor of 4 to 8: PSD is lowered by 3.0 dB

As can be observed in Examples 1 through 3, the PSD may be adjusted tomeet most PSD requirements.

An example of an extreme case is shown in Example 4, where the PSDcannot be lowered enough through normal means, so the bandwidth may beincreased while signal spreading is implemented.

Example 4 is a non-limiting example of bandwidth being increased whileall other parameters are held constant:

Bandwidth is increased by 2: PSD is lowered by 3.0 dB

Bandwidth is increased by 4: PSD is lowered by 3.0 dB

As can be observed, the PSD may be adjusted by any one of the manyparameters. Unlike an active antenna where the coefficients may beadjusted to reform (reconfigure) the beam, static antennas such as grid,parabolic, passive patch, etc. antennas cannot adjust(reform/reconfigure) their beams—only the entire power level may beadjusted to compensate for the PSD of the antenna.

The identification of the carriers on an adjacent satellite may be aidedby carrier identification technology as described in U.S. applicationSer. No. 13/024,402 to Beeler, et al., filed Feb. 10, 2011 and entitled“Embedded Meta-Carrier with Spread Spectrum via Overlaid Carriers”, andU.S. application Ser. No. 13/044,446, to Beeler, et al., filed Mar. 9,2011 and entitled “Embedded Meta-Carrier with Spread Spectrum forPeriodic-Burst Carriers via Overlaid Carriers”, the disclosures of whichare hereby incorporated in their entireties by this reference.

Additionally, FIG. 7 shows how a particular embodiment of the methodsmay be used to overcome inband interference. As part of the monitoringfeature for the ASI, the inband interference may be monitored resultingin this embodiment being used to overcome link degradation due tointerference or deteriorating conditions. In the event the desiredsignal 700 is being interfered with 710, the method may adjust themodulation, coding, power, spreading and bandwidth of the desired signalin an attempt to overcome the inband interference resulting in analtered desired carrier 720. As an example, increasing the bandwidthwhile using spread spectrum technology may result in overcoming inbandinterference.

FIG. 8 shows an implementation of a logic flow that may be brought tobear for iteratively attempting to address the PSD being monitored. AsFIG. 8 demonstrates, the logic attempts to exhaust the modulation index800 first, FEC rates 810 and spread factors 820. In particularimplementations as illustrated through FIG. 8, the power may beconstantly adjusted to find the optimal value that lowers the PSD to anacceptable level. In the final iterations, the bandwidth 830 of theterminal's carrier may be adjusted with the spread factor and power as afinal attempt to control the emission from the terminal. In one extremeexample, this feedback path may also be used to turn off thetransmission power of the terminal. This may use spread spectrum orembedded spread spectrum as the method of communications transport.

FIG. 9 shows an implementation of a logic flow that may be brought tobear for iteratively attempting to address the inband interference. AsFIG. 9 demonstrates, the logic attempts to exhaust the modulation indexfirst 900, FEC rates 910 and spread factors 920. In particularimplementations, the power may be constantly adjusted to find theoptimal value that overcomes the inband interference. In the finaliterations, the bandwidth 930 of the terminal's carrier may be adjustedwith the spread factor and power as a final attempt to overcome theinband interference experienced by the terminal. In one extreme example,this feedback path may also be used to turn off the transmission powerof the terminal. This may use spread spectrum or embedded spreadspectrum as the method of communications transport.

Since interference may be viewed as a form of degradation, any one ofthe following parameters may be brought to bear to address inbandinterference. As interference is experienced, the modulation index, FECcoding, power, spread factor or bandwidth may be adjusted to overcomeinterference resulting in link degradation.

Particular embodiments and implementations of the described methods arenot limited to a single direction in the traditional sense where a largeearth station is transmitting to a remote station (fixed or mobile), butmay be implemented in either or both directions across the link.

Through continued monitoring as the remote site provides feedback on thestatus of the received signal, the link parameters may be adjusted toprovide optimal conditions.

The following are particular implementations of a method for adaptivecontrol of modulation, Forward Error Correction (FEC) rate coding,power, spreading, and bandwidth for the control of a wirelesscommunications links for mitigating Adjacent Satellite Interference(ASI) and overcoming inband interference and are provided asnon-limiting examples:

Example 1

A small aperture mobile terminal is operating using a geostationarysatellite. A monitoring station using an embodiment of a describedmethod is monitoring the emissions from the terminal on the desiredsatellite and the adjacent satellites. The monitoring station determinesthe remote terminal is exceeding the power spectral density for properoperation and the resulting emissions are beyond the specified limitsand thus, is causing interference on an adjacent satellite. Themonitoring station instructs the mobile terminal to adjust themodulation index and associated power to correct the PSD on the adjacentsatellite.

Example 2

As described in Example 1, the mobile terminal has adjusted themodulation index to the lowest modulation index, but the monitoringstation determines the PSD is beyond the specified limits and thus, iscausing interference on an adjacent satellite. The monitoring stationinstructs the mobile terminal to adjust the FEC rate and associatedpower to correct the PSD on the adjacent satellite.

Example 3

As described in Example 1, the mobile terminal has adjusted the FEC rateto the lowest FEC rate, but the monitoring station determines the PSD isbeyond the specified limits and thus, is causing interference on anadjacent satellite. The monitoring station instructs the mobile terminalto adjust the spread factor and associated power to correct the PSD onthe adjacent satellite.

Example 4

As described in Example 1, the mobile terminal has adjusted the spreadfactor to the highest spread factor, but the monitoring stationdetermines the PSD is beyond the specified limits and thus, is causinginterference on an adjacent satellite. The monitoring station instructsthe mobile terminal to increase the bandwidth, spread factor andassociated power to correct the PSD on the adjacent satellite.

Example 5

As described in Example 1, the monitoring station can constantly adjustpower in an attempt to reverse the changes to lower the PSD in anattempt to increase the parameters resulting in restoring higher datathroughput.

Example 6

As described in Example 1, the center frequency may be moved to afrequency that may result in lower interference to adjacent satellites.

Example 7

As described in Example 1, the monitoring station can turn off thetransmission power of the mobile terminal.

Example 8

A small aperture terminal is operating using a geostationary satellite.A monitoring station using an embodiment of a described method ismonitoring the emissions from the terminal. The monitoring stationdetermines the remote terminal is receiving inband interfered which isresulting in a degraded signal from the terminal. The monitoring stationinstructs the terminal to adjust the modulation index and associatedpower to overcome the inband interference without causing ASI due toexceeding the PSD.

Example 9

As described in Example 8, the terminal has adjusted the modulationindex to the lowest modulation index, but the monitoring stationdetermines the terminal still may not overcome the interference or iscausing ASI using the modulation index changes. The monitoring stationinstructs the terminal to adjust the FEC rate and associated power toovercome the inband interference while monitoring the PSD on theadjacent satellite.

Example 10

As described in Example 8, the terminal has adjusted the FEC rate to thelowest FEC rate, but the monitoring station determines the terminalstill may not overcome the interference or is causing ASI using the FECrate changes. The monitoring station instructs the terminal to adjustthe spread factor and associated power to overcome the inbandinterference while monitoring the PSD on the adjacent satellite.

Example 11

As described in Example 8, the terminal has adjusted the spread factorto the highest spread factor, but the monitoring station determines theinterference cannot be overcome or is causing interference on anadjacent satellite. The monitoring station instructs the terminal toincrease the bandwidth, spread factor and associated power to overcomethe inband interference while monitoring the PSD on the adjacentsatellite.

Example 12

As described in Example 8, the monitoring station can constantly adjustpower in attempt to reverse the changes to overcome the inbandinterference and PSD in an attempt to increase the parameters resultingin restoring higher data throughput.

Example 13

As described in Example 8, the center frequency may be moved to afrequency that may result in lower interference to adjacent satellites.

Example 14

As described in Example 8, the monitoring station can turn off thetransmission power of the mobile terminal.

The invention claimed is:
 1. A method for dynamically controllingtransmission parameters for reducing inband interference, the methodcomprising: monitoring one or more signals emitted by one or more remotetransmitters; determining whether inband interference exists from atleast one of the one or more remote transmitters that is higher than apredetermined level of inband interference; and automaticallytransmitting a control signal to the remote transmitter in response to adetermination that the inband interference is higher than thepredetermined level of inband interference, the control signal adjustingone or more transmission parameters of the one or more remotetransmitters such that the inband interference is reduced; and whereinat least one of the one or more transmission parameters that is adjustedcomprises at least one of a modulation index, a forward error correctionrate, and a spread factor.
 2. The method of claim 1, wherein the one ormore remote transmitters are all located within a common network and areconfigured to communicate among the one or more remote transmitters. 3.The method of claim 1, wherein the one or more signals monitored areoff-axis signals and the monitoring occurs on one or more satellitesadjacent to a predetermined satellite to which the one or more signalsis to be transmitted.
 4. The method of claim 1, wherein at least one ofthe one or more transmission parameters is a power spectral density ofthe one or more signals transmitted by the one or more remotetransmitters.
 5. The method of claim 1, wherein at least one of the oneor more transmission parameters is a signal bandwidth.
 6. The method ofclaim 1, wherein at least one of the one or more transmission parametersis a center frequency.
 7. A system for dynamically controllingtransmission parameters for reducing inband interference, the systemcomprising: a monitoring device configured to monitor one or moresignals emitted by a remote transmitter and determine whether inbandinterference exists that is higher than a predetermined level of inbandinterference; and a transmitter configured to transmit a control signalto the remote transmitter in response to a determination that the inbandinterference is higher than the predetermined level of inbandinterference, the control signal configured to adjust one or moretransmission parameters such that the inband interference is reduced;and wherein at least one of the transmission parameters that is adjustedcomprises at least one of a modulation index, a forward error correctionrate, and a spread factor.
 8. The system of claim 7, wherein the one ormore remote transmitters are all located within a common network and areconfigured to communicate among the one or more remote transmitters. 9.The system of claim 7, wherein the monitoring device is located on oneor more satellites adjacent to a predetermined satellite to which theone or more signals is to be transmitted and further configured tomonitor one or more off-axis signals.
 10. The system of claim 7, whereinat least one of the one or more transmission parameters is a powerspectral density of the one or more signals transmitted by the remotetransmitter.
 11. The system of claim 7, wherein at least one of the oneor more transmission parameters is a signal bandwidth.
 12. The system ofclaim 7, wherein at least one of the one or more transmission parametersis a center frequency.